Draft device for furnaces



Sept. 29, 1925.

J. STUBBLEFIELD DRAFT DEVICE FOR FURNACES Filed April 30, 1925 jwuwl'o'oJ Siu65l efiela? @311 WWW EM L w E L? T Patented Sept. 29, 1925.

UNITED STATES PATENT OFFICE.

JOHN STUBBLEFIELD OF COLUMBUS, NEBRASKA, ASSIGNOR OF ONE-FOURTH T0 WIL-LIAM H. STUIBBLEFIELD AND ONE-FOURTH TO HENRY R. 'SEIDEL, BOTH OF COLUM-BUS, NEBRASKA.

DRAFT DEVICE FOR FURNACES.

To all whom it may concern:

Be it known that I, JOHN STUBBLEFIELD, a citizen of the Unitedv States,residing at Columbus, in the county of Platte and State of Nebraska,have invented certain new and useful Improvements in Draft Devices forFurnaces, of which the following is a specification, reference being hadto the accompanying drawings.

This invention relates to furnaces, and particularly to the draftdevices thereof.

It is usual in installing heating furnaces in houses to place them inthe cellar or furnace room, these heating furnaces having draft openingsprovided with dampers or doors, which draft openings open directly intothe cellar or furnace room. As a consequence, the air which is deliveredto the fire is usually contaminated and lacks oxygen, the oxygen havingbeen used up by the fire itself, and thus the best results are notsecured from the furnace under these circumstances but the fire isliable to be dull and the combustion imperfect and much less heat issecured than should be secured and much more labor entailed. In order toavoid this it is more or less common to open a door or window from theoutside to admit outside air into the cellar or furnace room but thisacts to chill the furnace and to chill those pipes which pass throughthe furnace room, thus wasting heat and necessitating a greater amountof coal being-burned.

The object of my invention is to provide a furnace and particularlyfurnaces such as are used in large houses and apartments or plants oflike character with a pipe which extends from a draft door to theoutside air, this pipe being provided with a damper whereby a sufficientsupply of fresh air with its full quota of oxygen is provided for thefurnace.

A further object in this connection is to provide an attachment of thisnature which may be applied to any furnace for thispurpose.

My invention is illustrated in the accompanying drawing, wherein Figure1 is a front elevation of a furnace of common construction showing mycold air draft appliance thereon in section;

Figure 2 is a vertical sectional view through the cold air draftappliance, the furnace being partly broken away.

Referring to this drawing, it will be seen that I have illustrated acommon form of furnace, this furnace not constituting any part of myinvention and merely being to illustrate an application of my invention.This furnace A is of the over draft type, that is, it has a draftopening B- which is disposed below the level of the fire but above thegrate C. Below the grate there are disposed the ash doors D and abovethe grate the clinker doors E in this form of furnace. Disposed in theupper portion of the furnace are the feed doors F. The stack isdesignated G and the draft up the stack is regulated by means of a checkdraft damper of the usual character. It will be understood that I do notwish to limit myself to this particular form of furnace but I havemerely illustrated a common type.

My invention consists in applying at the draft opening B the casing orhead 10 having therein a controlling damper 11,- and from this casing orhead extends a pipe 12 which extends vertically for a distance and thenis angularly bent at 13 and extends out through the adjacent wall of thebasement and opens to the fresh air so that the fresh air can passthrough this pipe and down to the head 10 and thus be discharged intothe interior of the furnace preferably, in the form of furnaceillustrated, at a point just above the fire.

This head 10, as illustrated, is designed to fit over the rectangularbox-like frame I which defines the inlet opening B, and inwardly of thisopening there is a downwardly extending baflle wall Z2 which may extendthe entire length of the furnace and which acts to deflect the airlongitudinally through the length of the furnace and downwardly to aposition beneath the fire but above the grate.

While I have illustrated this fresh air draft pipe and head as beingapplied to .one type of furnace, it is intended that the head shall beso formed as to fit the draft door frames of different furnaces andheads may be made and kept in stock for the standard forms of furnaces.Thus, for instance, in a furnace where the fresh air is admitted to thefire through the lower draftdoor or through a draft damper in the furnace base, the fresh air head 10 will be designed to fit the opening orthe projecting flange defining said opening. By controlling the damper11, the amount of fresh air entering the fire Will be controlled in theusual manner.

By means of my appliance pure, fresh air is piped directly from theoutside of the building into the combustion chamber of the furnace andby drawing this pure, fresh air through the fire causes it to Warm up bythe time it comes in and by mixing plenty of this pure, fresh air withthe gases they are burned up and the fuel Waste practically eliminatedand fuel smoke also disappears. Atmospheric air includes approximately20% of oxygen, While the air in the average furnace room is probably aslow in oxygen content as 12% or 15%, and it has been found by actualexperiments and tests that a difference of 2% of oxygen in the airpassing into a fire will make a very great difference in thecompleteness of its combustion. I have found in actual practice thatthis is the case. For instance, in the particular building in Which thefurnace I have experimented on is located, there are two boilers, thefurnace being of the magazine feed down-draft type. The fuel recommendedfor this furnace is #3 free burning soft coal. During the past Winter intesting this device I used in this furnace a rather poor quality ofslack lignite coal. It has been heretofore very difficult With bothfurnaces going to heat the building, but this past Winter With myappliance attached to one of the furnaces and the other furnacecompletely idle with no fire in it at all, and burning the poorest slacklignite coal, the building hasbeen kept very Warm even in the coldestWeather and at leastthirty tons of coal have been saved. It will,therefore, be seen that my invention is of practical value and greatlyreduces the consumption of coal as Wellas adding to .the heat generatedby the coal. Obviously,

the installation will be modified to suit circumstances of operation. a

I claim The combination With a furnace having a draft opening disposedabovethe grate and below the normal level of the fuel bed, the draftopening being defined outwardly extending Walls and the Walls'carrying adamper, of a pipehaving a head at one end fitting over the outwardlyextending Walls of the draft opening, the other end of the pipeextending to the exterior of the bulldmg and opening lnto a source ofpure, rresh air.

In testimony whereof I hereunto affix my signature.

